Understood.It's ebonite, but since no material is without drawbacks the rubber/acrylic argument boils down to personal preference.
Meaning, by saying "perfectly conceived and executed" I did not mean to imply that Jesse invented and uses some proprietary substance that's without flaws, merely that he chose an industry-standard material and then used it perfectly.
I've a bamboo-shank Tsuge with a rubber stem, but plastic on both ends of the bamboo. That was nice attention to detail, I thought. I know it's a personal preference, but I think it ought to be standard practice for plastic only on the shank when the color choice is black. I can't think of a reason why rubber is required there. It's easier to to take the green out of a removable stem than out of a permanently fixed shank piece.
I do like Jesse's art, both in pipes and facial hair.